Focal adjustable hologram lens and optical apparatus using the same

Abstract

Provided is a hologram lens including a holographic plate and first and second electrodes. The holographic plate is formed of a material having a refractive index which varies according to an electro-optic effect and has a hologram recorded thereon to serve as a lens. First and second electrodes are formed on front and back surfaces of the holographic plate to apply an electrical field to a hologram area of the holographic plate in which at least the hologram is recorded. A focal point is adjusted depending on the strength of the electrical field applied to the hologram area. Accordingly, a hologram lens can be made of a material having a variable refractive index and recording a hologram thereon so that the hologram lens serves as a lens. Thus, in the hologram lens, a focal point can vary depending on the strength of an electrical field applied to a hologram area.

What is claimed is:  
     
         1 . A hologram lens comprising; 
 a holographic plate formed of a material having a refractive index which varies according to an electro-optic effect and having a hologram recorded thereon to serve as a lens; and    first and second electrodes disposed on front and back surfaces of the holographic plate to apply an electrical field to a hologram area of the holographic plate in which at least the hologram is recorded,    wherein a focal point of the hologram lens is adjusted depending on a strength of the electrical field applied to the hologram area.    
     
     
         2 . The hologram lens of  claim 1 , wherein the holographic plate is formed of one selected from the group consisting of a polymer liquid crystal, a dichromated gelatin, a silver-halide emulsion, a photoresist, and a non-linear holographic recording material.  
     
     
         3 . The hologram lens of  claim 2 , wherein the non-linear holographic recording material is one of photopolymer, LiNbO 3 , and BSO.  
     
     
         4 . An optical apparatus including a lens system having at least one lens and adjusting at least one of a focal point and a magnifying power, the lens system comprising: 
 a holographic plate formed of a material having a refractive index which varies according to an electro-optic effect and having a hologram recorded thereon to serve as one of said at least one lens; and    first and second electrodes disposed on front and back surfaces of the holographic plate to apply an electrical field to a hologram area of the holographic plate in which at least the hologram is recorded,    wherein a focal point of the one of said at least one lens is adjusted depending on a strength of an electrical field applied to the hologram area.    
     
     
         5 . The optical apparatus of  claim 4 , wherein the holographic plate is formed of one selected from the group consisting of a polymer liquid crystal, a dichromated gelatin, a silver-halide emulsion, a photoresist, and a non-linear holographic recording material.  
     
     
         6 . The optical apparatus of  claim 5 , wherein the non-linear holographic recording material is one of photopolymer, LiNbO 3 , and BSO.  
     
     
         7 . The optical apparatus of  claim 5 , wherein the optical apparatus is used in an optical recording and/or reproducing apparatus and a hologram lens including the holographic plate and first and second electrodes is used as an objective lens for focusing incident light as a light spot on an optical recording medium, so that a magnetic circuit for adjusting a focal position of the objective lens in a focusing direction is excluded.  
     
     
         8 . The optical apparatus of  claim 4 , wherein the optical apparatus is used in an optical recording and/or reproducing apparatus and a hologram lens including the holographic plate and first and second electrodes is used as an objective lens for focusing incident light as a light spot on an optical recording medium, so that a magnetic circuit for adjusting a focal position of the objective lens in a focusing direction is excluded.  
     
     
         9 . The optical apparatus of  claim 5 , wherein the lens system is one of a zoom lens system, a focal adjustable lens system, a compound lens system of a camera, and a compound lens system of a video camera.  
     
     
         10 . The optical apparatus of  claim 4 , wherein the lens system is one of a zoom lens system, a focal adjustable lens system, a compound lens system of a camera, and a compound lens system of a video camera.